The present invention belongs to the field of textile components for the manufacture of composite materials. More particularly, the present invention relates to textile structures capable of serving as reinforcements in composite materials. It also relates to technical yarns or threads of novel configuration which are intended for such structures.
It is known that composite materials are formed from an intimate combination of reinforcing textile structures and impregnating resins or matrices. Such materials are widely employed at present, for example in the aeronautical industry. In order to obtain materials having the desired properties, it is necessary to use a relatively high proportion of textile structure, in particular by building up various reinforcing layers. It is known, however, that the impregnation of such reinforcing layers by the resins is not achieved optimally. Owing to the effect of mechanical stresses, this results in damage to the composite material due to a separation of certain layers within the textile reinforcement which is known to those skilled in the art as "delamination". It will be understood that, in view of the applications of such composite materials, it is essential to remedy such disadvantages.
One of the means proposed in the prior art to overcome such disadvantages consists, at least partly in the textile reinforcement, of a multidimensional, for example three-dimensional, structure. Such structures are satisfactory but they are expensive and take a long time to fabricate.
It may be said that the current criteria for choosing a textile structure serving as reinforcement of composite materials are: the nature of the yarns, the distribution and orientation of the latter, and also their method of use (for example in the form of woven structures or unidirectional laps). These criteria are used as a function of the desired properties for the composite material.